Civil Engineering Reference
In-Depth Information
Fig. 12-8.
Typical pressure filter (Courtesy of USFilter / Memco)
media is often used. The increase in water depth will provide more available head to
lengthen filter runs and enable flexibility to change to alternate filter media in the
future should it become necessary. A minimum water depth of 6 feet above the surface
of the filter media should be provided, with 2-3 feet of freeboard allowed for in the
filter design. The overall depth of the filter box will be affected by the type of under-
drain and depth of filter media that are used, so the depth of filters cannot be finalized
until those elements are selected.
The use of common walls between filtered and unfiltered water should be avoided
so as to eliminate the possibility of contamination of the finished water. For the same
reason, it is better not to construct clearwell storage beneath the pipe gallery floor.
Many states do not permit these types of construction.
